[docs] Remove devextreme-reactive

[oliviertassinari]

🚨It just came to my attention that dx-react-grid-material-ui isn't free software in the modern meaning of the phrase. It's licensed under a custom license. People have to pay for commercial applications.

While I'm very happy to see that Material-UI is responsible for a 84% of the success of dx-react-grid, I think that we will better of not promoting the link in the current situation and warning about the potential confusion in the next release note:

1. It can be confusing for our users. They would expect us to promote MIT licensed like libraries. It took me 8 months to realized it's not free software: [docs] Advanced table #7824.
2. There is a business opportunity. It can be leveraged in order to keep Material-UI model sustainable.

cc @kvet and @gsobolev